/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package javax.servlet.http;



/**
 * HttpSessionBindingEvent是HttpSessionAttributeListener和HttpSessionBindingListener的事件类，包含了属性的名称和属性的值
 *
 * HttpSessionBindingEvent由HttpSessionBindingListener和HttpSessionAttributeListener公用.
 * 在会话中绑定或取消绑定时，HttpSessionBindingEvent发送给HttpSessionBindingListener.
 * 当在会话中绑定、取消绑定或替换任何属性时，HttpSessionBindingEvent发送给HttpSessionAttributeListener.
 *
 * 会话通过调用HttpSession.setAttribute并解除对象绑定，
 * 通过调用HttpSession.removeAttribute.
 *
 * Events of this type are either sent to an object that implements
 * {@link HttpSessionBindingListener} when it is bound or 
 * unbound from a session, or to a {@link HttpSessionAttributeListener} 
 * that has been configured in the deployment descriptor when any attribute is
 * bound, unbound or replaced in a session.
 *
 * <p>The session binds the object by a call to
 * <code>HttpSession.setAttribute</code> and unbinds the object
 * by a call to <code>HttpSession.removeAttribute</code>.
 *
 *
 *
 * @author		Various
 *
 * 
 * @see 		HttpSession
 * @see 		HttpSessionBindingListener
 * @see			HttpSessionAttributeListener
 */

public class HttpSessionBindingEvent extends HttpSessionEvent {




    /**
     * 要绑定或取消绑定对象的名称.
     * The name to which the object is being bound or unbound
	 */

    private String name;
    
    /**
	 * 要绑定或取消绑定对象.
	 * The object is being bound or unbound
	 */

    private Object value;
    
  

    /**
     *
     * Constructs an event that notifies an object that it
     * has been bound to or unbound from a session. 
     * To receive the event, the object must implement
     * {@link HttpSessionBindingListener}.
     *
     *
     *
     * @param session 	the session to which the object is bound or unbound
     *
     * @param name 	the name with which the object is bound or unbound
     *
     * @see			#getName
     * @see			#getSession
     *
     */

    public HttpSessionBindingEvent(HttpSession session, String name) {
	super(session);
	this.name = name;
    }
    
    /**
     *
     * Constructs an event that notifies an object that it
     * has been bound to or unbound from a session. 
     * To receive the event, the object must implement
     * {@link HttpSessionBindingListener}.
     *
     *
     *
     * @param session 	the session to which the object is bound or unbound
     *
     * @param name 	the name with which the object is bound or unbound
     *
     * @see			#getName
     * @see			#getSession
     *
     */
    
    public HttpSessionBindingEvent(HttpSession session, String name, Object value) {
	super(session);
	this.name = name;
	this.value = value;
    }
    
    
   	/**
	 * 获得HttpSession.
	 * Return the session that changed.
	 */
    public HttpSession getSession () { 
	return super.getSession();
    }
 
   
  
    
    /**
     * 获得要绑定或取消绑定对象的名称.
     * Returns the name with which the attribute is bound to or
     * unbound from the session.
     *
     *
     * @return		a string specifying the name with which
     *			the object is bound to or unbound from
     *			the session
     *
     *
     */

    public String getName() {
	return name;
    }
    
    /**
	 * 获得要绑定或取消绑定对象.
	 *
	 * Returns the value of the attribute that has been added, removed or replaced.
	 * If the attribute was added (or bound), this is the value of the attribute. If the attribute was
	 * removed (or unbound), this is the value of the removed attribute. If the attribute was replaced, this
	 * is the old value of the attribute.
	 *
	 * @since 2.3
	 */
	
	public Object getValue() {
	    return this.value;   
	}
    
}







